An airbag module with the above-mentioned features is known from WO 03/006276 A2. For keeping the ventilation opening closed before and also during the inflation of the airbag and for only allowing the ventilation opening to be released at a certain time, a type of retaining strap is provided in the known airbag module and fixed with one end to the airbag fabric in the region of the adaptive ventilation opening, which fabric on one hand completely covers the ventilation opening in its starting or mounted position and closes it, and which on the other hand is fixed with its other end to a module-side retaining device in such a manner that the relevant end of the retaining strap is released when the retaining device is triggered. The retaining strap has dimensions such that it completely covers the ventilation opening. The retaining strap is furthermore guided with its free end towards the releasable retaining device in the form of a bolt which can be blasted off and fixed to the bolt with a loop formed at the end. The length of the retaining strap is such that, when the airbag is folded up, the region of the airbag fabric which is overlapped by the retaining strap with the ventilation opening which is arranged therein and sealed off by the retaining strap is held fast and thus cannot assume its stretched position when the airbag is inflated. In addition, tear seams are provided for fixing the retaining strap in its mounted position. The retaining strap releases the fabric region which has the ventilation opening only after the retaining device has been activated and the end of the retaining strap fixed thereon is released, so that the region, which is fixed by the retaining strap, of the airbag completely unfolds and completely opens the adaptive ventilation opening owing to the stretching of the airbag fabric, wherein at the same time the retaining strap is removed from the opening so that the ventilation opening is released.
The known airbag module entails the disadvantage that the arrangement of the retaining strap must be matched to the respective side of the adaptive ventilation opening after dimensioning and fixing; furthermore the assembly of the airbag including of the retaining strap to be attached to it in the airbag is complex.